JP4158802B2 - Fixing apparatus and image forming apparatus - Google Patents

Abstract

A fixing device includes a pressure thermister for detecting temperature of a pressure roller. The fixing device also includes a thermal coating member on the opposite side of the pressure roller with respect to the pressure thermister. The thermal coating member has a thermal conductivity of 10W/m.K or more. The heat from the pressure roller is easily transferred to the thermal coating member because of the high thermal conductivity, so that the thermal coating member becomes warm quickly. This increases a temperature rise rate in the pressure thermister and therefore reduces time taken for warm-up of the fixing device.

Description

  The present invention relates to a fixing device used in an electrophotographic image forming apparatus such as a copying machine, a laser printer, and a facsimile, and an image forming apparatus using the fixing device.

  Conventionally, there is a fixing device that detects the temperature of the surface of the heating roller with a non-contact type temperature sensor (see JP-A-6-19367: Patent Document 1). This temperature sensor is covered and protected by the cover member from the side opposite to the heating roller. This cover member is generally made of resin.

  However, in the conventional fixing device, since the cover member is made of resin, the thermal conductivity and thermal reflectance of the cover member are small. And since the heat conductivity of the said cover member is small, the heat from the said heating roller is hard to be transmitted to the said cover member, the warming of the said cover member becomes slow, and the heat from the said heating roller is from the said temperature sensor. , Escapes to the cover member, and the temperature rise of the temperature sensor is delayed. Further, since the heat reflectance of the cover member is small, the radiant heat from the heating roller is not easily reflected by the cover member and is not effectively transmitted to the temperature sensor.

  Therefore, the responsiveness of the temperature sensor to the temperature rise of the surface temperature of the heating roller is poor, and it is not possible to shorten the time taken for the operation to raise the temperature of the surface of the heating roller to a temperature capable of fixing (hereinafter referred to as warm-up) It was.

That is, when the heating roller is heated in a short time by shortening the warm-up time, the temperature sensor cannot detect the temperature of the heating roller with good responsiveness. Overheating occurs. If this heating roller overheats, the fixing quality of the recording material, the durability of the heating roller, and the safety of preventing the ignition of the heating roller cannot be ensured.
Japanese Patent Laid-Open No. 6-19367 (FIG. 5)

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device capable of shortening the warm-up time while ensuring quality, durability and safety.

In order to solve the above problems, the fixing device of the present invention is:
A pair of rotating bodies that fix the toner of the recording material while conveying the recording material in contact with each other;
A heating unit for heating at least one of the rotating bodies;
A temperature detector that detects the surface temperature of at least one of the rotating bodies at a position spaced from the surface of the rotating body;
With respect to the temperature detection unit, a thermal coating member disposed on the opposite side to the rotating body on the detected side whose temperature is detected by the temperature detection unit,
The thermal conductivity of the thermal covering member state, and are more 10 W / m · K,
The temperature detection unit has a temperature detection surface facing the detected rotation body,
The thermal covering member includes a bowl-shaped portion whose distance from the surface of the detected rotating body is substantially the same as the distance between the temperature detection surface and the surface of the detected rotating body,
This hook-shaped portion is characterized by extending along the rotation axis direction of the detected side rotating body .

  According to the fixing device of the present invention, since the thermal conductivity of the thermal coating member is 10 W / m · K or more, the thermal conductivity of the thermal coating member is high. Heat is easily transferred to the thermal covering member. Thus, the warming of the thermal covering member is accelerated, the transfer of heat from the temperature detecting unit to the thermal covering member is suppressed, and the temperature rising rate of the temperature detecting unit is increased.

Therefore, the responsiveness of the temperature detection unit to the temperature rise of the surface temperature of the detection side rotating body is improved, and the operation of raising the temperature of the surface of the detection side rotation body to a fixable temperature (hereinafter referred to as warm-up). ) Can be shortened. In other words, by shortening the warm-up time, the temperature detecting unit can detect the temperature of the detected side rotating body with high responsiveness even if the detected side rotating body rises in a short time. For example, it is possible to prevent an excessive temperature increase of the detected rotating body. By preventing excessive temperature rise of the detected rotating body, the quality of fixing of the recording material, the durability of the detected rotating body, and the safety of preventing the ignition of the detected rotating body are improved. It can be secured. In addition, since the thermal covering member includes a portion in which the distance from the surface of the detected rotating body is substantially the same as the distance between the temperature detection surface and the surface of the detected rotating body, Heat from the detected rotating body can be transmitted to the thermal covering member substantially simultaneously with the temperature detection surface, and the warming of the thermal covering member can be further accelerated. Therefore, the responsiveness of the temperature detection unit to the temperature rise of the surface temperature of the detected rotating body is further improved, and the warm-up time can be further shortened.

  In one embodiment, the fixing device includes a protection member that covers and protects the temperature detection unit from the opposite side of the detected rotation body with respect to the temperature detection unit, and the thermal covering member is the protection member. And the thermal conductivity of the thermal covering member is larger than the thermal conductivity of the protective member.

  According to the fixing device of this embodiment, since the protection member that protects the temperature detection unit is provided, the user cannot be touched by the protection member and accidentally touch the temperature detection unit. Prevent damage. Further, the temperature detection unit can be accurately measured without being affected by dust or wind in the apparatus.

  Further, since the thermal conductivity of the thermal covering member is larger than the thermal conductivity of the protective member, the thermal conductivity of the thermal covering member can be reliably improved and the warm-up time can be shortened reliably. That is, even if the protective member is formed of a resin, for example, the thermal conductivity of the protective member can be made larger than the thermal conductivity of the resin, and the thermal conductivity of the thermal covering member can be increased.

  In the fixing device according to an embodiment, the thermal covering member also serves as a protective member that covers and protects the temperature detection unit from the opposite side of the detected rotation body with respect to the temperature detection unit.

  According to the fixing device of this embodiment, since the thermal covering member also serves as the protective member, it is possible to reduce the number of components and reduce the size of the device.

  In the fixing device according to the embodiment, the heat reflectance of the one surface of the thermal covering member on the temperature detection unit side is larger than the heat reflectance of the one surface of the protection member on the temperature detection unit side. .

  According to the fixing device of this embodiment, since the reflectance of the one surface of the thermal covering member is larger than the reflectance of the one surface of the protective member, the radiant heat from the detected rotating body is It can be reflected on the one surface of the thermal covering member and transmitted to the temperature detection unit.

  Therefore, the temperature increase rate of the temperature detection unit is increased, the responsiveness of the temperature detection unit to the temperature increase of the surface temperature of the detected rotating body is further improved, and the warm-up time can be further shortened. That is, even if the protective member is made of, for example, a resin, the reflectance of the protective member can be made larger than the reflectance of the resin, and the thermal reflectivity of the thermal covering member can be increased.

The fixing device of the present invention is
A pair of rotating bodies that fix the toner of the recording material while conveying the recording material in contact with each other;
A heating unit for heating at least one of the rotating bodies;
A temperature detector that detects the surface temperature of at least one of the rotating bodies at a position spaced from the surface of the rotating body;
A protective member that covers and protects the temperature detection unit from the opposite side of the detected rotating body on which the temperature is detected by the temperature detection unit with respect to the temperature detection unit;
A thermal covering member disposed between the protective member and the temperature detection unit;
Thermal reflectivity of one surface of the temperature detecting portion side of the thermal covering member, than the reflectance of heat one surface of the temperature detecting portion side of the protective member, rather large,
The temperature detection unit has a temperature detection surface facing the detected rotation body,
The thermal covering member includes a bowl-shaped portion whose distance from the surface of the detected rotating body is substantially the same as the distance between the temperature detection surface and the surface of the detected rotating body,
The hook-shaped portion extends along the rotation axis direction of the detected rotating body .

  According to the fixing device of the present invention, since the reflectance of the one surface of the thermal covering member is larger than the reflectance of the one surface of the protection member, the radiant heat from the detected rotating body is converted to the heat. It can be reflected on the one surface of the target covering member and transmitted to the temperature detecting unit.

  Therefore, the temperature increase rate of the temperature detection unit is increased, the responsiveness of the temperature detection unit to the temperature increase of the surface temperature of the detected rotating body is improved, and the warm-up time can be shortened. That is, by shortening the warm-up time, the temperature detecting unit can detect the temperature of the detected rotating body with high responsiveness even if the detected rotating body rises in a short time. For example, it is possible to prevent an excessive temperature increase of the detected rotating body. By preventing excessive temperature rise of the detected rotating body, the fixing quality of the recording material, the durability of the detected rotating body, and the safety of preventing the ignition of the detected rotating body can be ensured. .

  Moreover, even if the protective member is formed of, for example, a resin, the reflectance of the protective member can be made larger than the reflectance of the resin, and the thermal reflectivity of the thermal covering member can be increased.

Moreover, since the protective member which protects the said temperature detection part is provided, a user cannot get in contact with the said temperature detection part accidentally by being disturbed by the said protective member, and prevents the damage of the said temperature detection part. Further, the temperature detection unit can be accurately measured without being affected by dust or wind in the apparatus. In addition, since the thermal covering member includes a portion in which the distance from the surface of the detected rotating body is substantially the same as the distance between the temperature detection surface and the surface of the detected rotating body, Heat from the detected rotating body can be transmitted to the thermal covering member substantially simultaneously with the temperature detection surface, and the warming of the thermal covering member can be further accelerated. Therefore, the responsiveness of the temperature detection unit to the temperature rise of the surface temperature of the detected rotating body is further improved, and the warm-up time can be further shortened.

  In one embodiment, the thermal reflectance of one surface of the thermal coating member on the temperature detection unit side is higher than the thermal reflectance of one surface of the temperature detection unit on the thermal coating member side. ,large.

  According to the fixing device of this embodiment, since the reflectance of the one surface of the thermal coating member is larger than the reflectance of the one surface of the temperature detection unit, the reflectance is reflected by the one surface of the thermal coating member. Radiant heat from the detected rotating body can be prevented from being reflected by the one surface of the temperature detecting unit and returning to the one surface of the thermal covering member.

  Therefore, the radiant heat reflected by the one surface of the thermal covering member can be effectively transmitted to the temperature detection unit, the temperature increase rate of the temperature detection unit can be increased, and the surface temperature of the detected rotating body can be increased. The responsiveness of the temperature detection unit with respect to the temperature is further improved, and the warm-up time can be further shortened.

In the fixing device according to an embodiment, the temperature detection unit covers the heat sensitive element and the heat sensitive element from the opposite side to the detected side rotating body with respect to the heat sensitive element, and heat from the detected side rotating body. And a heat collecting part that collects heat and conducts the heat-sensitive element.
The thermal covering member covers the heat collecting part and is at least as large as the heat collecting part when viewed from the opposite side of the detected rotating body with respect to the thermal covering member.

  According to the fixing device of this embodiment, the thermal covering member covers the heat collecting portion and is at least as large as the heat collecting portion when viewed from the opposite side of the detected rotating body with respect to the thermal covering member. Thus, the thermal covering member can be made small, and the cost can be reduced.

In the fixing device according to the embodiment, the heat reflectance of the one surface of the heat collecting portion on the thermal coating member side is higher than the heat reflectance of the one surface of the thermal coating member on the temperature detecting portion side. Small .

  In the fixing device of one embodiment, the thermal covering member extends longer than the temperature detection unit and covers the temperature detection unit in the rotation axis direction of the detected rotating body.

  According to the fixing device of this embodiment, the thermal covering member extends longer than the temperature detection unit and covers the temperature detection unit in the rotation axis direction of the detection-side rotating body. Responsiveness of the temperature detection unit to the temperature rise of the surface temperature of the detected rotating body is further improved, and the warm-up time can be further shortened.

  In the fixing device of one embodiment, the thermal covering member extends longer than the temperature detection unit and covers the temperature detection unit in the rotation direction of the detection side rotating body.

  According to the fixing device of this embodiment, the thermal covering member extends longer than the temperature detection unit and covers the temperature detection unit in the rotation direction of the detection-side rotating body. The responsiveness of the temperature detection unit to the temperature rise of the surface temperature of the detected rotating body is further improved, and the warm-up time can be further shortened.

  An image forming apparatus according to the present invention includes the fixing device.

  According to the image forming apparatus of the present invention, since the fixing device is provided, the warm-up time can be shortened while ensuring the quality, durability and safety.

  According to the fixing device of the present invention, since the thermal coating member having high thermal conductivity or high thermal reflectance is provided, the warm-up time can be shortened while ensuring the quality, durability and safety.

  Further, according to the image forming apparatus of the present invention, since the fixing device is provided, the warm-up time can be shortened while ensuring the quality, durability and safety.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

(First embodiment)
FIG. 1 is a simplified configuration diagram showing a first embodiment of a fixing device according to the present invention. The fixing device includes a heating side rotating body 1 and a pressure side rotating body 2. The heating side rotating body 1 is heated by a heating side heater 15 as a heating unit, and the pressure side rotating body 2 is heated by a pressure side heater 25 as a heating unit.

  The pair of rotating members 1 and 2 fix the toner t of the recording material S while contacting the other and conveying the recording material S. More specifically, a nip is formed by contact between the heating-side rotator 1 and the pressure-side rotator 2, and the toner t of the recording material S is melted and fixed by the nip. The recording material S is conveyed.

  The recording material S is, for example, a sheet such as paper or an OHP sheet. A toner t is attached to one surface of the recording material S, and the toner t is made of a material having heat melting properties such as a resin, a magnetic material, or a colorant.

  The heating-side rotator 1 includes a heating roller 11, a backup member 13, and a belt 12 that is wound around the heating roller 11 and the backup member 13.

  The heating roller 1 is a metal core such as aluminum. The outer diameter of the heating roller 1 is, for example, 30 mm.

  The belt 12 has a base material layer, an elastic layer, and a release layer from the inside to the outside. The base material layer is made of a material having strength such as aluminum, iron, or polyimide. The elastic layer is made of a material having heat resistance and elasticity such as rubber, resin, or silicon rubber. The release layer is made of a material having release properties and heat resistance, such as silicon rubber, fluorine rubber, PFA, PTFE, FEP, or PFEP. The belt 12 includes, for example, from the inside to the outside, polyimide having an outer diameter of 50 mm and a thickness of 70 μm, silicon rubber having a thickness of 200 μm, and a PFA tube having a thickness of 20 μm.

  The backup member 13 has a small friction coefficient on the contact surface with the belt 12, and is made of, for example, resin. The backup member 13 is in contact with the pressure-side rotating body 2 through the belt 12 to form the nip portion. The outer surface of the backup member 13 forming this nip portion is formed in a concave shape. For example, the pack-up member 13 has a thickness of 4 mm, and the belt 12 has a circumferential width of 12 mm. The radius of curvature of the concave outer surface is 15.4 mm.

  The backup member 13 is provided with a reinforcing member 14 that supports the backup member 13 from the inside. The reinforcing member 14 is made of stainless steel, for example.

  The pressure-side rotating body 2 is a pressure roller 20. The pressure roller 20 includes a support layer 21, an elastic layer 22, and a release layer 23 from the inner side to the outer side in the radial direction. The support layer 21 is, for example, an iron core bar having an outer diameter of 30 mm. The elastic layer 22 is, for example, silicon rubber. The release layer 23 is, for example, a fluorine resin such as PFA having a thickness of 30 μm. The pressure roller 20 is rotated by a driving unit such as a motor (not shown), and the belt 12 is rotated by the rotation of the pressure roller 20 by friction with the pressure roller 20.

  The pressure roller 20 is pressed against the backup member 13 with a load of 100 to 530N. In this case, the width dimension of the nip portion (the dimension in the rotation direction of the pressure roller 20) is about 9 mm. The length of the nip portion (the dimension of the pressure roller 20 in the rotation axis direction) is about 240 mm. Of course, the width and length of the nip may be changed by changing the load.

  The heating-side heater 15 is disposed inside the heating roller 11 and heats the heating roller 11 and the belt 12 from the inside. The pressure side heater 25 is disposed inside the pressure roller 20 and heats the pressure roller 20 from the inside. For example, the heaters 15 and 25 raise the belt 12 and the pressure roller 20 to a temperature at which the toner t of the recording material S can be fixed.

  A heating thermistor 16 as a temperature detection unit is provided outside the heating roller 11. The heating thermistor 16 is in contact with the surface of the heating roller 11 and detects the surface temperature of the heating roller 11.

  A pressure thermistor 26 as a temperature detector is provided outside the pressure roller 20. The pressure thermistor 26 detects the surface temperature of the pressure roller 20 at a position separated from the surface of the pressure roller 20.

  Here, since the pressure thermistor 26 is a non-contact sensor, the surface of the pressure roller 20 is not damaged, the durability of the pressure roller 20 can be improved, and image noise can be prevented.

  The heating roller 11 and the pressure roller 20 are respectively controlled by a control unit (not shown) so as to maintain a predetermined temperature based on the outputs of the heating thermistor 16 and the pressure thermistor 26.

  As shown in FIGS. 2A and 2B, the pressure thermistor 26 is attached to the casing 5 to which the pressure roller 20 is attached. The pressure thermistor 26 has a temperature detection surface 260 facing the pressure roller 20.

  A protective member 3 is provided on the opposite side of the pressure thermistor 26 from the pressure roller 20. The protection member 3 covers and protects the pressure thermistor 26 from the side opposite to the pressure roller 20.

  This protection member 3 is formed from resin. The protection member 3 includes a box portion 31 having a rectangular bottom surface and a flange portion 32 provided at an opening end of the box portion 31.

  The box part 31 is, for example, a rectangular parallelepiped having a width of 30 mm × 30 mm, a height of 20 mm, and a thickness of 2 mm. The flange portion 32 is provided on both sides of the opening end of the box portion 31 in the axial direction of the pressure roller 20. The flange portion 32 extends along the axial direction of the pressure roller 20.

  Since the protective member 3 is provided, the user can not touch the pressure thermistor 26 by being obstructed by the protective member 3 at the time of paper clogging, and the pressure thermistor 26 is prevented from being damaged. To do. Further, the pressure thermistor 26 can be accurately measured without being affected by dust and wind in the apparatus.

  A thermal covering member 4 is provided between the protective member 3 and the pressure thermistor 26. That is, the thermal covering member 4 is attached to the inner surface of the protective member 3. Specifically, the thermal covering member 4 is attached to the inner surface of the box portion 31 and the surface of the flange portion 32 facing the pressure roller 20.

  The thermal conductivity of the thermal covering member 4 is 10 W / m · K or more, which is larger than the thermal conductivity of the resin, 0.2 W / m · K. That is, the thermal conductivity of the thermal covering member 4 is larger than the thermal conductivity of the protective member 3.

  Further, the heat reflectance of the one surface 4a of the thermal covering member 4 on the pressure thermistor 26 side is larger than the heat reflectance of the one surface 3a of the protective member 3 on the pressure thermistor 26 side. Further, the heat reflectance of the one surface 4a of the thermal covering member 4 on the pressure thermistor 26 side is larger than the heat reflectance of the one surface 26a of the pressure thermistor 26 on the thermal coating member 4 side. .

  The thermal covering member 4 is made of aluminum, for example. Specifically, the thermal covering member 4 is an aluminum foil or aluminum tape having a thickness of about 15 μm. The thermal coating member 4 may be provided on the inner surface of the protection member 3 by coating or plating, or the thermal coating member 4 is attached to the inner surface of the protection member 3 with a double-sided tape. May be attached.

  The thermal covering member 4 includes a portion where the distance from the surface of the pressure roller 20 is substantially the same as the distance between the temperature detection surface 260 and the surface of the pressure roller 20. That is, the thermal covering member 4 on the flange portion 32 is located on the substantially same plane as the temperature detection surface 260.

  As shown in FIG. 2A, the thermal covering member 4 extends longer than the pressure thermistor 26 in the rotational direction of the pressure roller 20 and covers the pressure thermistor 26. As shown in FIG. 2B, the thermal covering member 4 extends longer than the pressure thermistor 26 in the direction of the rotation axis of the pressure roller 20 and covers the pressure thermistor 26.

  As shown in FIGS. 3A and 3B, the pressure thermistor 26 is attached to an attachment portion 261 attached to the casing 5, a frame portion 262 fixed to the attachment portion 261, and a bottom surface of the frame portion 262. It has the holding | maintenance part 263, the thermal element 264 installed in the upper surface of this holding | maintenance part 263, and the heat collecting part 265 which covers this thermal element 264 from an upper surface. Here, the bottom surface side means the pressure roller 20 side. That is, the bottom surface of the holding portion 263 corresponds to the temperature detection surface 260.

  The heat collecting unit 265 fixes the thermal element 264 to the holding unit 263. The heat collecting unit 265 collects heat from the pressure roller 20 and conducts it to the heat sensitive element 264. The heat reflectance of the one surface 265a of the heat collecting member 265 on the thermal coating member 4 side is smaller than the heat reflectance of the one surface 4a of the thermal coating member 4.

  Next, the operation of this fixing device will be described with reference to FIG.

  First, the temperature of the fixing device is adjusted. That is, an operation of raising the temperature of the surface of the belt 12 and the surface of the pressure roller 20 to a fixable temperature (hereinafter referred to as warm-up) is performed.

  Here, the warm-up is performed immediately after the apparatus is turned on, when the jam processing is restored, when the cover of the apparatus is opened or closed, or when the sleep mode is restored.

  The heating side heater 15 and the pressure side heater 25 are turned on to raise the surface temperatures of the belt 12 and the pressure roller 20.

  The pressure roller 20 is thick in the support layer 21 and the elastic layer 22 and cannot be heated up to the surface of the pressure roller 20 in a short time with only the pressure-side heater 25. Further, the heating side heater 15 can heat only a part of the heating roller 11 and the belt 12.

  Therefore, by rotating the pressure roller 20 and rotating the belt 12 and the heating roller 11 in a driven manner, the heat of the heating roller 11 is transmitted to the entire belt 12 and the surface of the pressure roller 20. .

  Thus, the temperature at which the surface of the belt 12 and the surface of the pressure roller 20 can be fixed in a shorter time due to the lighting of the heaters 15 and 25 and the rotation of the belt 12 and the heating roller 11. Can rise to.

  Here, when the temperature detected by the pressure thermistor 26 is T, the correction coefficient is R, and the temperature after correction is T ′, the relationship T ′ = R × T is satisfied. The corrected temperature T ′ is used for control related to temperature adjustment.

  When the temperature detected by the heating thermistor 16 and the corrected temperature T ′ detected by the pressure thermistor 26 reach a predetermined temperature, the ready indicates that fixing is possible. For example, when the temperature detected by the heating thermistor 16 is 190 ° C. and the corrected temperature T ′ by the pressure thermistor 26 is 120 ° C., ready is indicated.

  If there is no print signal, the print standby state is entered. If there is a print signal, the print operation is started. Here, printing refers to printing by this printer when this fixing device is used in a printer.

  In the standby state, the rotation of the belt 12 and the pressure roller 20 is normally stopped, and the heaters 15 and 25 are controlled so that the belt 12 and the pressure roller 20 have a predetermined set temperature.

  At the time of printing, by rotating the belt 12 and the pressure roller 20 from the start of printing and before the recording material S enters the fixing device, the heat of the heating roller 11 is increased. Conducted by the pressure roller 20, the temperature of the pressure roller 20 is increased.

  Next, the toner t of the recording material S is fixed by the fixing device. The recording material S is fed into the nip portion formed by contact between the belt 12 and the pressure roller 20. On the one surface of the recording material S, the unfixed toner t adheres.

  In the nip portion, the one surface of the recording material S is heated while being pressed to melt and fix the unfixed toner t. At the same time, the recording material S is transported by applying a transport force to the other surface of the recording material S by the rotation of the pressure roller 20. At this time, the belt 12 rotates following the conveyance of the recording material S.

  According to the fixing device having the above-described configuration, the thermal conductivity of the thermal coating member 4 is 10 W / m · K or higher, and thus the thermal conductivity of the thermal coating member 4 is high. Is easily transferred to the thermal covering member 4. Thus, the warming of the thermal covering member 4 is accelerated, the transfer of heat from the pressurized thermistor 26 to the thermal covering member 4 is suppressed, and the heating rate of the pressurized thermistor 26 is increased. .

  Accordingly, the responsiveness of the pressure thermistor 26 to the temperature rise of the surface temperature of the pressure roller 20 is improved, and the time required for warm-up can be shortened. That is, by shortening the warm-up time, the pressure thermistor 26 can detect the temperature of the pressure roller 20 with high responsiveness even if the pressure roller 20 rises in a short time. Thus, for example, excessive temperature rise of the pressure roller 20 can be prevented. By preventing the temperature rise of the pressure roller 20, the quality of fixing of the recording material S, the durability of the pressure roller 20, and the safety of preventing the ignition of the pressure roller 20 can be ensured. .

  Moreover, since the thermal conductivity of the thermal covering member 4 is larger than the thermal conductivity of the protective member 3, the thermal conductivity of the thermal covering member 4 can be reliably improved and the warm-up time can be ensured. Can be shortened. That is, even if the protective member 3 is formed of a resin, for example, the thermal conductivity of the protective member 3 can be made larger than the thermal conductivity of the resin, and the thermal conductivity of the thermal covering member 4 can be increased. Can be high.

  Further, the thermal covering member 4 includes a portion where the distance from the surface of the pressure roller 20 is substantially the same as the distance between the temperature detection surface 260 and the surface of the pressure roller 20. The heat from the pressure roller 20 can be transmitted to the thermal coating member 4 substantially simultaneously with the temperature detection surface 260, and the warming of the thermal coating member 4 can be further accelerated.

  Therefore, the responsiveness of the pressure thermistor 26 to the temperature rise of the surface temperature of the pressure roller 20 is further improved, and the warm-up time can be further shortened.

  Further, since the thermal covering member 4 extends longer than the pressure thermistor 26 in the direction of the rotation axis of the pressure roller 20 and covers the pressure thermistor 26, Responsiveness of the pressure thermistor 26 to the temperature rise of the surface temperature is further improved, and the warm-up time can be further shortened.

  Further, since the thermal covering member 4 extends longer than the pressure thermistor 26 in the rotational direction of the pressure roller 20 and covers the pressure thermistor 26, the surface of the pressure roller 20 The responsiveness of the pressure thermistor 26 with respect to the temperature rise is further improved, and the warm-up time can be further shortened.

  Further, since the reflectance of the one surface 4 a of the thermal coating member 4 is larger than the reflectance of the one surface 3 a of the protective member 3, radiant heat from the pressure roller 20 is converted to the thermal coating member 4. It can be reflected on the one surface 4a and transmitted to the pressure thermistor 26.

  Therefore, the temperature increase rate of the pressure thermistor 26 is increased, the responsiveness of the pressure thermistor 26 to the temperature increase of the surface temperature of the pressure roller 20 is further improved, and the warm-up time can be further shortened. That is, even if the protective member 3 is formed of a resin, for example, the reflectance of the protective member 3 can be made larger than the reflectance of the resin, and the thermal reflectivity of the thermal covering member 4 can be increased. .

  Further, the reflectance of the one surface 4 a of the thermal coating member 4 is larger than the reflectance of the one surface 26 a of the pressure thermistor 26, so that the additive reflected by the one surface 4 a of the thermal coating member 4 is used. Radiant heat from the pressure roller 20 can be reflected by the one surface 26 a of the pressure thermistor 26 and prevented from returning to the one surface 4 a of the thermal covering member 4.

  Therefore, the radiant heat reflected by the one surface 4a of the thermal covering member 4 can be effectively transmitted to the pressure thermistor 26, the temperature increase rate of the pressure thermistor 26 is increased, and the surface of the pressure roller 20 is increased. The responsiveness of the pressure thermistor 26 with respect to the temperature rise is further improved, and the warm-up time can be further shortened.

  The thermal coating member 4 has a configuration in which the thermal conductivity of the thermal coating member 4 is 10 W / m · K or more, or the heat reflectance of the one surface 4 a of the thermal coating member 4. Is sufficient to satisfy at least one of the configurations in which the thermal reflectance of the one surface 3a of the protective member 3 is larger.

  The thermal covering member 4 only needs to extend longer than the pressure thermistor 26 in the rotation axis direction of the pressure roller 20 or the rotation direction of the pressure roller 20.

  Further, the thermal covering member 4 may cover the heat collecting portion 265 and have at least the same size as the heat collecting portion 265 when viewed from the side opposite to the pressure roller 20 with respect to the thermal covering member 4. . Therefore, the thermal covering member 4 can be made small, and the cost can be reduced.

(Second Embodiment)
4A and 4B show a second embodiment of the fixing device of the present invention. In this 2nd Embodiment, compared with the said 1st Embodiment, the shape of a protection member and a thermal coating member differs. The materials for the protective member and the thermal covering member are the same as those in the first embodiment.

  That is, the inner shape of the protection member 103 and the thermal covering member 104 of the second embodiment is a parabolic shape. The protective member 103 has a parabolic shape in which the position where the thermal element 264 of the pressure thermistor 26 is disposed is a focal point. The thermal covering member 104 is provided along the inner surface of the protective member 103.

  Therefore, the radiant heat from the pressure roller 20 can be focused on the thermal element 264 by the parabolic thermal coating member 104, and the responsiveness of the pressure thermistor 26 to the temperature increase of the pressure roller 20 can be improved. It can be further accelerated.

(Third embodiment)
5A and 5B show a third embodiment of the fixing device of the present invention. In the third embodiment, the shape of the thermal covering member is different from that in the first embodiment. The material of the thermal covering member is the same as that in the first embodiment.

  That is, the thermal covering member 204 of the third embodiment has a plate shape curved in the axial direction of the pressure roller 20. The thermal covering member 204 is formed in a parabolic shape or an arc shape in a cross section including the axis of the pressure roller 20. The thermal covering member 104 is attached to the inner surface of the rectangular parallelepiped protective member 203 with a gap.

  Therefore, the thermal covering member 204 can be made small, and the radiant heat from the pressure roller 20 can be effectively transmitted to the pressure thermistor 26.

  The curved shape of the thermal covering member 204 may be the parabolic shape described in the second embodiment.

(Fourth embodiment)
6A and 6B show a fourth embodiment of the fixing device of the present invention. In the fourth embodiment, the shape of the thermal covering member is different from that of the first embodiment. The material of the thermal covering member is the same as that in the first embodiment.

  That is, the thermal covering member 304 of the fourth embodiment has a plate shape curved in the rotation direction of the pressure roller 20. The thermal covering member 304 is formed in a parabolic shape or an arc shape in a cross section orthogonal to the axis of the pressure roller 20. The thermal covering member 304 is attached to the inner surface of the rectangular parallelepiped protective member 303 with a gap.

  Therefore, the thermal covering member 304 can be made small, and the radiant heat from the pressure roller 20 can be effectively transmitted to the pressure thermistor 26.

  The curved shape of the thermal covering member 304 may be the parabolic shape described in the second embodiment.

(Fifth embodiment)
7A and 7B show a fifth embodiment of the fixing device of the present invention. In the fifth embodiment, there is no protective member as compared with the first embodiment. The material of the thermal covering member is the same as that in the first embodiment.

  That is, the thermal covering member 404 of the fifth embodiment also serves as a protective member that covers and protects the pressure thermistor 26 from the side opposite to the pressure roller 20 with respect to the pressure thermistor 26.

  As the thermal covering member 404, a member having high thermal conductivity is used. For example, a thin metal member made of aluminum, copper, or the like is used as the thermal covering member 404.

  Accordingly, since the thermal covering member 404 also serves as the protective member, it is possible to reduce the number of parts and downsize the apparatus.

(Sixth embodiment)
FIG. 8 shows a simplified configuration diagram as an embodiment of the image forming apparatus of the present invention. The image forming apparatus includes an image forming device 80 that forms an image by attaching unfixed toner t to the recording material S, and the first embodiment in which the toner t is melted and fixed to the recording material S. The fixing device 81 is provided. This image forming apparatus is an electrophotographic 4-color printer.

  The image forming device 80 includes an intermediate transfer belt 61, four image forming units 51 that are arranged along the intermediate transfer belt 61 and that form toner images, and toner images formed by the image forming units 51. Are transferred to the intermediate transfer belt 61, and a secondary transfer portion 63 that transfers the image transferred to the intermediate transfer belt 61 to the recording material S is provided.

  The image forming unit 51 for forming a black (BK) toner image, the image forming unit 51 for forming a yellow (Y) toner image, the image forming unit 51 for forming a magenta (M) toner image, and The image forming units 51 for forming a cyan (C) toner image are arranged in order from the upstream side to the downstream side of the intermediate transfer belt 61.

  Each of the image forming units 51 includes a photosensitive drum 52, a charging unit 53 for uniformly charging the photosensitive drum 52, and an exposure unit 59 for performing image exposure on the charged photosensitive drum 52. And a developing section 54 for developing the electrostatic latent image formed by exposure with toner of each color.

  The image forming apparatus includes a control device 68 that controls the entire image forming apparatus, and an exposure control device 69 to which a signal corresponding to the image is sent from the control device 68. The exposure control device 69 drives each of the exposure units 59 according to each color.

  Next, the operation of this image forming apparatus will be described.

  The toner image developed on the photosensitive drum 52 of the image forming unit 51 is primarily transferred onto the intermediate transfer belt 61 by the primary transfer unit 62 at a contact position with the intermediate transfer belt 61.

  Each time the toner image transferred onto the intermediate transfer belt 61 passes through each image forming unit 51, each color is superimposed on it, and finally, a full-color toner image is transferred onto the intermediate transfer belt 61. Formed.

  Thereafter, the full-color toner image on the intermediate transfer belt 61 is secondarily transferred onto the recording material S by the secondary transfer unit 63 downstream of the intermediate transfer belt 61.

  The recording material S passes through the fixing device 81 on the downstream side of the conveyance path of the recording material S, whereby the toner image is fixed and discharged onto the paper discharge tray 66.

  The recording material S is stored in the lowermost cassette 67, and is conveyed one by one from the cassette 67 to the secondary transfer unit 63.

  The toner remaining on the photosensitive drum 52 after the primary transfer is removed by the cleaning unit 55 disposed downstream and collected from below the cleaning unit 55.

  The toner remaining on the intermediate transfer belt 61 after the secondary transfer is removed from the intermediate transfer belt 61 by the cleaning blade 65, conveyed by a conveyance screw (not shown), and collected in a waste toner container (not shown). The

  According to the image forming apparatus having the above-described configuration, since the fixing device 81 is provided, the warm-up time can be shortened while ensuring quality, durability, and safety. The fixing device described in any of the second to fifth embodiments may be used as the fixing device of the image forming apparatus.

  In addition, this invention is not limited to the above-mentioned embodiment. For example, the heating-side rotating body 1 may be a roller other than the belt. The pressure-side rotating body 2 may be a belt other than a roller.

  In addition, a temperature detecting unit that detects the temperature of at least one of the pair of rotating bodies 1 and 2 may be provided, and the thermal covering member may be provided in the temperature detecting unit. In addition to the thermistor, a thermocouple may be used as the temperature detection unit.

  If the toner t of the recording material S can be fixed, at least one of the pair of rotating bodies 1 and 2 may be heated.

  Further, the thermal coating member has a configuration in which the thermal conductivity of the thermal coating member is 10 W / m · K or more, or reflection of heat on one surface of the thermal coating member on the temperature detection unit side. What is necessary is just to satisfy | fill at least one structure of the structures that a rate is larger than the heat | fever reflectance of the one surface of the said temperature detection part side of the said protection member.

  The image forming apparatus may be any one of a monochrome / color copying machine, a printer, a FAX, and a complex machine of these.

1 is a cross-sectional view illustrating a first embodiment of a fixing device of the present invention. FIG. 3 is a cross-sectional view of the fixing device on the pressure side. FIG. 3 is a longitudinal sectional view on the pressure side of the fixing device. It is a top view of a pressure thermistor. It is sectional drawing of a pressure thermistor. FIG. 5 is a cross-sectional view of a fixing device according to a second embodiment of the present invention and a pressure side of the fixing device. FIG. 4 is a longitudinal sectional view of a fixing device according to a second embodiment of the present invention and a pressure side of the fixing device. FIG. 6 is a cross-sectional view of a fixing device according to a third embodiment of the present invention and a pressure side of the fixing device. FIG. 6 is a longitudinal sectional view of a fixing device according to a third embodiment of the present invention and a pressure side of the fixing device. FIG. 7 is a cross-sectional view of a fixing device according to a fourth embodiment of the present invention and a pressure side of the fixing device. FIG. 7 is a longitudinal sectional view of a fixing device according to a fourth embodiment of the present invention and a pressure side of the fixing device. FIG. 10 is a cross-sectional view of the fixing device according to a fifth embodiment of the present invention and a pressure side of the fixing device. FIG. 7 is a longitudinal sectional view of a fixing device according to a fifth embodiment of the present invention and a pressure side of the fixing device. 1 is a simplified configuration diagram showing an image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating side rotary body 11 Heating roller 12 Belt 15 Heating side heater (heating part)
16 Heating thermistor (temperature detector)
2 Pressure-side rotating body 20 Pressure roller 25 Pressure-side heater (heating unit)
26 Pressure thermistor (temperature detector)
26a one surface 260 temperature detection surface 264 heat sensitive element 265 heat collecting part 265a one surface 3,103,203,303 protective member 3a one surface 4,104,204,304,404 thermal coating member 4a one surface

Claims (11)

A pair of rotating bodies that fix the toner of the recording material while conveying the recording material in contact with each other;
A heating unit for heating at least one of the rotating bodies;
A temperature detector that detects the surface temperature of at least one of the rotating bodies at a position spaced from the surface of the rotating body;
With respect to the temperature detection unit, a thermal coating member disposed on the opposite side to the rotating body on the detected side whose temperature is detected by the temperature detection unit,
The thermal conductivity of the thermal covering member state, and are more 10 W / m · K,
The temperature detection unit has a temperature detection surface facing the detected rotation body,
The thermal covering member includes a bowl-shaped portion whose distance from the surface of the detected rotating body is substantially the same as the distance between the temperature detection surface and the surface of the detected rotating body,
The fixing device according to claim 1, wherein the hook-shaped portion extends along a rotation axis direction of the detected rotating body . The fixing device according to claim 1,
A protective member that covers and protects the temperature detection unit from the opposite side of the detected rotating body with respect to the temperature detection unit;
The thermal covering member is disposed between the protective member and the temperature detection unit,
The fixing device according to claim 1, wherein a thermal conductivity of the thermal covering member is larger than a thermal conductivity of the protective member. The fixing device according to claim 1,
The fixing device according to claim 1, wherein the thermal covering member also serves as a protective member that covers and protects the temperature detection unit from the side opposite to the detected rotating body with respect to the temperature detection unit. The fixing device according to claim 2,
The fixing device according to claim 1, wherein the thermal reflectance of one surface of the thermal covering member on the temperature detection unit side is larger than the thermal reflectance of the one surface of the protective member on the temperature detection unit side. A pair of rotating bodies that fix the toner of the recording material while conveying the recording material in contact with each other;
A heating unit for heating at least one of the rotating bodies;
A temperature detector that detects the surface temperature of at least one of the rotating bodies at a position spaced from the surface of the rotating body;
A protective member that covers and protects the temperature detection unit from the opposite side of the detected rotating body on which the temperature is detected by the temperature detection unit with respect to the temperature detection unit;
A thermal covering member disposed between the protective member and the temperature detection unit;
Thermal reflectivity of one surface of the temperature detecting portion side of the thermal covering member, than the reflectance of heat one surface of the temperature detecting portion side of the protective member, rather large,
The temperature detection unit has a temperature detection surface facing the detected rotation body,
The thermal covering member includes a bowl-shaped portion whose distance from the surface of the detected rotating body is substantially the same as the distance between the temperature detection surface and the surface of the detected rotating body,
The fixing device according to claim 1, wherein the hook-shaped portion extends along a rotation axis direction of the detected rotating body . In the fixing device according to claim 1 or 5,
The fixing device according to claim 1, wherein the thermal reflectance of the one surface of the thermal covering member on the temperature detection unit side is larger than the thermal reflectance of the one surface of the temperature detection unit on the thermal coating member side. In the fixing device according to claim 1 or 5,
The temperature detector is
A thermal element;
A heat collecting unit that covers the heat sensitive element from the opposite side to the detected rotating body and collects heat from the detected rotating body and conducts it to the heat sensitive element with respect to the heat sensitive element,
The fixing device according to claim 1, wherein the thermal covering member covers the heat collecting portion and is at least as large as the heat collecting portion when viewed from the side opposite to the detected rotating body with respect to the thermal covering member. . The fixing device according to claim 7 ,
The fixing device according to claim 1, wherein a heat reflectance of one surface of the heat collecting unit on the side of the thermal coating member is smaller than a heat reflectance of one surface of the thermal coating member on the side of the temperature detection unit . In the fixing device according to claim 1 or 5,
The fixing device according to claim 1, wherein the thermal covering member extends longer than the temperature detection unit and covers the temperature detection unit in a rotation axis direction of the detected rotating body. In the fixing device according to claim 1 or 5,
The fixing device according to claim 1, wherein the thermal covering member extends longer than the temperature detection unit and covers the temperature detection unit in the rotation direction of the detected rotating body.   An image forming apparatus comprising the fixing device according to claim 1.

Images